I love this photo. If I'm not mistaken, you can pick out the internal structure of the bomb. You can also see the plasma (?) running down the support structures ahead of the fireball.

Incredible photograph. Wish we could go back and re-shoot this same stuff in 5K stereo. Looking at this reminds me of the picture of the cosmic background radiation that one physicist called the "face of God" For some reason I intuitively feel that there's some deep mystery in this picture.

For any of you in the vicinity of New Mexico, I encourage you to go visit the Atomic Museum, which is now known as the "The National Museum of Nuclear Science & History"

It's interesting to see the lack of symmetry in the photograph. I wonder how much of that results from the initial arrangement of fissile materials in the bomb, and how much from turbulence as the explosion occurred?

Photographs taken years ago at this level of time resolution must be helpful today in validating computer simulations of nuclear explosions. Simulations, rather than actual tests, are how the ongoing safety of the nuclear arsenals of the major nuclear powers is currently assessed.

While it is somewhat due to the makeup of the bomb and the environment at the time, fusion physicists are discovering that such instabilities in the explosion are extremely difficult to get rid of. Even in the NIF, which is a controlled environment with no air and a perfectly symmetric fusion target, they'se seeing images that look creepily similar to this one. Unfortunately, that means that creating an efficient fusion reactor is...more challenging that expected.

> The resulting extraordinary photographs revealed intricate details of the first instant of an atomic explosion, including a few surprises such as irregular “mottling” caused primarily by variations in the density of the bomb’s casing. It also showed the detail of the “rope trick effect,” where the rapid vaporization of support cables caused curious lines to emanate from the bottom of an explosion.

The camera is interesting - using an electronic not mechanical shutter. This was around 1944. (Bell Lab's transistor was around 1947.)

More interesting still -- the mottling is from the remains of the casing and the shot cab (the little building the bomb was housed in at the top of the tower) splashing against the shock front at the fireball's boundary.

This is what impresses me so much about this photo. I think of nuclear bomb fissile materials as being one of the most precise things ever humans have ever made, yet the the fireball is so incredibly irregular.

It reminds me of when I first learned that irregularity in the early universe is what enabled material to condense (probably not the best word) and eventually form gas clouds.

Edit: I was wondering if there was some connection between the two, but thanks to DanBC's comment, it seems like the actual cause is a lot less mysterious.

Implosion-type nuclear bombs (which are nearly all of them) use a mind-bogglingly precise sphere of fissile material. If you put a drop of thin oil on top and came back a few hours later, the oil would coat the sphere evenly.

The way the explosion works isn't exactly a single, expanding nucleus of hot material. It's pretty complicated, but what's going on at this point is that the bomb is giving off x-ray radiation, which is absorbed the air, heating it up. As a consequence of air absorbing the radiation, air further from the bomb is shielded from the radiation. The sphere that you see is, approximately, the air close enough (un-blocked enough) to absorb enough heat to glow in the visible spectrum.

The upshot of this is that the entire sphere that you see comes into existence in a roughly simultaneous fashion, not in an expanding fashion. If you watch slow-motion videos, you will see that sphere stay at the same size and transition from dark to light, rather than start light and transitioning from small to large.

The explosion itself comes later, as that air (which is around 9000F) obeys basic gas laws, and tries to expand.

It says, "the fireball...is three times hotter than the surface of the sun". Won't you get toasted from only 7 miles afar? Or, maybe the fireball is ephemeral so the heat the fireball produced doesn't do damage?

Meaning that at 20m from the center of the explosion (the fireball was 20m diameter, or 10m radius) it should already be at 1/4 the intensity, already less than the surface of the sun. At 7 miles or 11200m, you're talking 1/(1120^2) or 7.97e-7 of the original intensity - effectively zero - if I've done that math right.

Let's not forget, apart from distance, the fireball is expanding in all directions. At 1" from the center, you're exposed to half the fireball. At 1 mile from the center, you're exposed to a tiny spherical arc of the fireball.

The energy is going in every direction, not just at you. With distance, you will receive a smaller portion of whatever energy made it 7 miles out.

It doesn't maintain the temperature for very long, so there's surprisingly little total heat energy transferred over that time. If the camera were behind a barrier and took the picture in a mirror (as is often done with explosions), it could be within 2 miles of a large-ish atom bomb without taking much damage. http://www.nebraskastudies.org/0900/frameset_reset.html?http...

it's been a long time since i've studied physics and physical chemistry so i could be wayyyy off but ...

how i understand it is two-fold. first, heat density. the surface area of the explosion is significantly smaller than the sun, and so the energy in the explosion is condensed to a smaller area and thus creates a higher temperature. as it expands it will, therefore, "cool" (relatively speaking) and by the time it reaches 7 miles away it wont melt the piss out of the camera (it obviously survived).

second is the spread of heat from the explosion to the camera. heat transfer is not instantaneous, and so the camera was just fine at this point. again, by the time it spreads to the camera it's dissipated so much energy that the heat will be relatively cooler.

finally i imagine the camera was pretty well protected to withstand the various forces of the explosion.

I am also wondering how we can blow up something 3 times hotter than the surface of the Sun so close. Then again, the "surface" of the Sun is orders of magnitudes cooler than its center. The "surface", which is kind of hard to define, is about 5778K, but the centre is about 1.571 x 10^7 K. [1]

I don't think there is a current Edgerton exhibit at the MIT Museum although there may be some photos. Strobe Alley (fourth floor of Building 4) does however have a permanent exhibit of photographs and some other things.

(For others, the context here is that in addition to his work photographing and filming nuclear explosions, Edgerton also developed the electronic strobe along with developing lots of other interesting things, and going on Jacques Cousteau expeditions. (Also a wonderful teacher and person.)

That would be a Planck time, but 1) we can't measure with a precision anywhere remotely close to that, and 2) if we could time things that finely, we couldn't take a photograph of it because there isn't enough time for the photons to hit your receptor. For perspective, this photo took more than a decillion Planck times.

(Disclaimer: I'm not a physicist of any sort, but I'm pretty sure this is all right.)